Method and apparatus for igniting explosive charges



June 18, 1935. HOLZWARTH 2,004,945

METHOD AND APPARATUS FOR IGNITING EXPLOSIVE CHARGES Filed April 25, 19534 Sheets-Sheet l Coourva MED/um 'l/Vl/ENTOR flTTOR/VEY June 18, 1935. H.HOLZWARTH METHOD AND APPARATUS FOR IGNITING EXPLOSIVE CHARGES FiledApril 25, 1953 4 Sheets-Sheet 2 M an m 200 up :10 3'20 0 4 0' u m m 250m m .320

HTT'ORNEY METHOD AND APPARATUS FOR IGNITING EXPLOSIVE CHARGES FiledApril 25, 1953 4 Sheets-Sheet 3 JTI y M 5 v TR M 0 NW/ 0 M Hz w H mm A 6H 7 7N A H June 18,

H. HOLZWARTH' METHOD AND APPARATUS FOR IGNI'I'ING EXPLOSIVE CHARGESFiled April 25, 1933 4 Sheets-Sheet 4 Patented June 18, 1935 2,004,945

Meruon AND APPARATUS FOR IGNITING EXPLOSIVE CHARGES Hans Holzwarth,Dusseldorf, Germany, assignor to Holzwarth Gas Turbine 00., SanFrancisco, Calif., a corporation of Delaware Application April 25, 1933,Serial No. 667,820 In Germany April 27, 1932 21 Claims. (CI. 60-41) Thepresent invention relates to an improved is directly in contact with thecomparatively method of accomplishing the periodic ignition minutespark. Moreover, the surface of the of combustible charges of fuel andair intermitspark is extremely small in comparison with the tentlyintroduced into an explosion chamber, size of the charge in the chamber.The combuswhereby more rapid and complete combustion of tion of themixture in the chamber thus proceeds such charges is obtained. from thissmall surface of the igniting spark Briefly described, my inventioninvolves the as a sheet of flame which takes the form of a ignition of acharge of fuel and air along the spherical shell of constantlyincreasing radius extensive dividing plane or zone between the havingits center at the point of ignition, in a ignitable mixture comprisingthe new charge and manner similar to that in which sound waves, 10 abody of hot gas, which may be either scavengwhen unobstructed, spreadout in air from the ing air or residual gases or both, confined orsource of the sound in concentric spherical surtrapped at the outlet endsection of the explosion faces. The burning surface developing in thechamber, and maintained at or raised to a temfuel and air mixture thusenlarges as the comperature sufficient to effect ignition of thecombustion proceeds. From this it follows that a 15 bustible mixture inthe manner described more combustion process initiated by ignition at afully hereinbelow. point requires a great deal of time because of theThe invention relates in particular to the oporiginally very smalligniting surface of this eration of elongated explosion chambers, andignition point. If the fuel mixture, furthermore,

particularly of elongated constant volume explocontains dimcultlyburning fuel which must be 20 sion chambers employed in explosionturbines, decomposed or dry-distilled before the ignition, provided withair and fuel inlet members at one the combustion process lasts evenlonger because end thereof, and outlet mechanism at the oppotheenlargement of the burning area, proceeding site end thereof, in whichchambers preferably from the igniting spark, occurs comparativelygaseous or liquid, but if desired also solid fuel slowly. There istherefore required a certain 25 is burned by explosion, the resultingexplosion time interval before a sufllciently large and efgases beingthen discharged from the chamber fective igniting area forms in thecombustible and all of their available energy utilized outside mixture.Where liquid fuels are employed, the such chamber. quantity of heatrequired for vaporizing and gasi- The invention has for its primaryobject to fying the fuel must be abstracted from the inte- 30 acceleratethe ignition and the course of comrior of the already burning portion ofthe charge bustion of the fuel and air mixture in explosion 'andtransferred by radiation to the still unchambers of the type indicatedas contrasted burned part of the charge, which of course is with knownprocesses. It is also an object of very large at the beginning of thecombustion.

the invention to make it possible to determine In this way there iswithdrawn from the just- 35 the instant of ignition in the most exactmanner mentioned burning portion of the charge, solarge and to controlthe instant of ignition, that is, a quantity of heat that itstemperature falls to make such ignition controllable in suchmanconsiderably. This temperature reduction leads her that the ignitionof the fuel and air mixture to slow and incomplete combustion. Todeteroccurs with certainty only after the charging of mine the magnitudeof the heat withdrawal in- 40 the explosion chamber with the materialsthat volved, a mixture consisting of liquid benzol and "support thecombustion is completed. air in the ratio of 1:325 was investigated andI have found that the usual method of ignition it was found bycalculation that by the evaporaof a fuel-air mixture with the aid of anelectric tion alone of the liquid benzol its surroundings spark has twofundamental disadvantages, both were cooled by more than 20 C. 'Withsome 45 of which are attributable to the very small ordinary fuels afurther cooling occurred due igniting surface presented by the electricspark. to the endothermic chemical breaking up of the Investigation hasshown that, in the first place, fuel particles prior to the combustionof the mixthere is no assurance that, even when the fuel ture. Iffurther, the fuel and air mixture is has been homogeneously distributedthrough the ignited, asis usual, by means of a spark, in 50 air charge,the fuel and air mixture will become which the ignition surface, asabove explained, ignited directly, that is, immediately, after theassumes .the form of a burning spherical shell appearance of the spark,because there is no which grows constantly larger as the combus absolutecertainty that the instant when the tion proceeds and by which the fuelsurrounding spark is struck an ignitable part of the mixture the same onall sides must be evaporated and decomposed, the resulting cooling isincreased many fold.

The present invention provides a new and improved process for theignition of mixtures containing liquid, gaseous or even powdered fuels,

whereby the disadvantages of the known processes are overcome and thecombustion process very materially improved. My improved process ispreferably carried out in elongated, constant volume explosion chambersand consists essentially in confining or trapping, between the outletmember of the explosion chamber and the fresh fuel and air mixtureintroduced. into the chamber for the next charge, a body of gases ofsuch a temperature that the mixture of fuel and air ignites along thesurface of the gases facing the same, that is, along the plane ofcontact between such trapped gases and said mixture. The

gases serving for the ignition of the fuel and air mixture may, forexample, consist of residual explosion gases which have been retained inthe chamber from the preceding explosion cycle of the explosion chamber,and may have been mixed, if desired, with air; such gases may howeveralso consist of air which has been highly heated by radiation and by thedirect transfer of heat by conduction. My improved method of operationhas above all the great. advantage that a comparatively large ignitingsurface is presented right from the beginning by the trapped ignitinggases to the fresh mixture of fuel and air introduced into the chamber,such igniting surface being practically perpendicular or nearly so tothe longitudinal axis of the chamber when the latter is of elongatedcylindrical form, the surface being capable of being itself curved.

My novel process can of course beaided to a considerable degree by ahigh temperature in the parts located in the region of the ignitinggases and especially in the wall itself of the explosion chamber whichis heated in any suitable manner. A high temperature at such parts isnot only valuable for effecting a high degree of heat radiation into theigniting gases located at such place' and thereby insuring theirigniting temperature, but these parts represent a sort of heat storageapparatus which is capable of yielding that quantity of heat which isnecessary with certain fuels for the vaporization and decomposition oftheir constituents before the ignition. In this way a measure isprovided which guards against the withdrawal of the whole quantity ofheat required for the vaporization and decomposition of the fuelparticles from the combustion process itself. In other words, theatmosphere surrounding the fuel particles is prevented from becoming toocool.

As already indicated, my improved process can best be carried out in anelongated explosion chamber which is as nearly cylindrical as possible,such as had already been proposed by me,

for constant volume explosion turbines, the inlet members for theoperating media (the fuel and ,air) being located at one end of theexplosion the explosion and expansion are completed, may be displaced bythe air subsequently entering the chamber in the manner of a piston. Bythe conical formation of the outlet end of the chamber the transversecross-section of the chamber continuously diminishes with the result*thatsuch a high velocity is imparted to the combustion gases uponopening of the outlet member that the heat transfer at the outlet end ofthe chamber is gradually increased. The gases which are to serve for theignition of the fuel and air mixture, and which are located at theoutlet end of the chamber between the outlet valve and the incoming bodyof air, are preferably provided in such quantity that they fill ascompletely as possible the rear or outlet conical end of the chamber, sothat the dividing surface (the igniting surface) between the ignitinggases and the fuel and air mixture is located, upon the initiation ofthe ignition, in the neighborhood of the connection between the outletconical end and the middle, elongated cylindrical portion of thechamber. In this way the result is attained that the kindling of themixture from here on proceeds at all points of the ignition surfacelinearly toward the chamber inlet end, whereby a heat transfer from theburning core of the contents of the chamber to the mixture to be burnedoccurs only at the surface of the burning core, facing the mixture to beburned, the area of which latter surface is limited by the circumferenceof the elongated portion of the chamber, and is very small in comparisonwith such core, in contrast with the known type of ignition by means ofan electric spark, in which the spherically shaped igniting surface,which grows continually larger as the combustion proceeds, is materiallylarger than the igniting means itself. 1

For heating the igniting gas confined at the outlet end of the chamber acertain amount of combustion gas residue may be with advantage retainedat 'such end, such gases being trapped at the outlet end of the chamber,during the expulsion of the residual combustion gases during thescavenging of theexplosion chamber while the outlet member is open, byadvancing the moment of closing of the latter. My improved process iscarried out with particular advantage both when the explosion chamber isof considerably elongated form, and much time is provided for scavengingthe chamber of the residual gases except the portion thereof which is toserve for igniting the next charge. Under these conditions there willoccur, even during the scavenging step, a strong radiation of heat fromthe combustion gases into the adjoining portion of scavenging orsuper-charging air advancing from the inlet side of the chamber.

1 My novel process affords certain and complete combustion in everyparticular of any mixture of fuel and air in a preferably elongatedexplosion chamber, as the mixture in the chamber comes into contact fromthe beginning of the ignition on, with an extraordinarily large ignitingsurface of a temperature sufficient to effect ignition, such temperaturebeing increased, if desired, by additional radiation of heat. Because ofthe large available igniting surface, the ignition of the mixture occurswith great rapidity and rapid combustion of the whole contents of thechamber is accomplished. My new process makes it possible to burn fuelsso completely (which fuels can be burned, for example, in Diesel motorswith difficulty and very incompletely) that I backfire into the inletvalves and feeding conit is not possible, even with chemical means, todetect any unburned constituents of the mixture after the combustion inthe chamber. In particular, even those fuels canbe burned completelywithout odor which in known combustion processes burn only incompletelyand consequently, as is known, produce gases having an unpleasant odor.

In the application of my new-process to explosion chambers for powerplants, as for example, explosion turbines, in which, because the loadand speed of such plants may change greatly and frequently, the chargingconditions of the explosion chamber may change suddenly and abruptly,there may be arranged additional igniters in the chamber, such as, forexample, constantly glowing parts, or, still better, controlled electricspark devices whereby failure of ignition is avoided with certainty.Such auxiliary igniters may with advantage be employed for starting theexplosion chamber from the cold condition. Where positively controlledelectric spark plugs are employed as auxiliary igniters, they arepreferably controlled in such manner that they are fired after theinstant at which ignition is to be effected, in the normal operation ofthe chamber, by the igniting gases confined therein. Such controllableauxiliary igniters cannot disturb the normal ignition by the confinedigniting gases, but they insure the ignition of the mixture in the eventthat the normal ignition by the igniting gases fails for any reason.

The use of auxiliary igniters does not, however, always sufllce toproduce a disturbance-free starting operation with difiicultly ignitiblefuel, In such case the condition of the mixture at the instant ofignition must, during the starting operation, be made to approach asclosely as possible to the condition during normal operation. Thisresult can be secured by the use of the process and means provided withthe present invention whereby the outlet end of the chamber isartificially pre-heated and in this way the temperature of the body ofgas (air and/or residual gases) confined thereat is increased byradiation, or else by heating the scavenging and charging air before itsentry into the explosion chamber.

In a further development of the inventive idea, my improved process maybe carried out by making the time interval, during which the fuelmixture advances from the inlet end of the chamber toward the outletend, that is, toward the igniting surface, controllable at will in sucha manner that the instant at which the ignition of the mixture occurscan be exactly predetermined. By this measure the ignition of themixture is prevented before the charging of the chamber with acombustible mixture of proper quantity and composition is completed.Should the ignition of the mixture occur before the inlet members of thechamber are closed, the pressure gases generated by the explosion wouldbe forced into the conduits in advance of the inlet members and displacethe operating media (e. g. fuel and air) contained therein. Should thisoccur, there would be charged into the chamber during the next cycle, atleast at first, uncombustible constituents originating from thecombustion gases, or combustion supporting air mixed with combus'tiongases, so that an incomplete and unsatisfactory mixture would beformedin the chamber and proper operation of the chamber would berendered impossible.

Moreover, when combustion gases frequently duits, the inlet end of thecombustion chamber becomes so strongly heated that the new fuel and air'mixture forming at the beginning of a charge becomes ignited at suchinlet end, so that the combustion is initiated even more prematurelythan before and the whole process is completely deranged.

These disadvantages can be overcome by vari- I ous measures inaccordance with the further development of the present invention. Onepossibility of avoiding the difliculties resides in the propermeasurement of the velocity of the vehicle which carries fuel, suchvehicle being usually air. This measure can be carried out in asatisfactory manner by displacing the beginning of the fuel introductioninto.the chamber with reference to the introduction of the air. Thisprocedure is based upon the observation that the highest air velocity inthe chamber is attained right at the beginning of the air admission intothe chamber, that is, shortly after the opening of the air inlet valve,since upon opening of such valve the difference between the pressure ofthe incoming air and the back pressure in the chamber is greatest. Theback pressure becomes gradually higher as the charging of the chamberproceeds, so that the velocity of the incoming air falls proportionally.Hence, upon coincidence of the beginning of the introduction of fuel andair, the fuel meets air of the highest velocity in the chamber,the fuelparticles'first entering the chamber being thus carried by the air atvery high velocity toward the chamber outlet, that is, toward theigniting place. If, now the fuel is introduced into the chamber acertain time interval after the will be the time required before suchfuel par-' ticles traverse the distance between the mouth of the fuelinlet member and the igniting place at the outlet end of the chamber;that is, the greater will be the time interval available prior toignition for terminating the introduction of' air and fuel into thechamber and closing the corresponding inlet members at the proper timebefore the ignition actually takes place.

By the increase of the time interval between the beginning of the fuelinjection and the ignition by retarding the beginning of the injection,it is however possible for the injection to begin only after thecharging of the explosion chamber with air has proceeded too far, sothat the velocity of the air, because of the increase of the backpressure as the charging of the chamber proceeds, has fallen to a valueat which proper atomization of the fuel is no longer possible. In suchcase there can, in accordance with the invention, be selected anothersimple 'way of correctly dimensioning the interval from the beginning ofthe fuel injection to the instant of ignition of the mixturein thedescription, following this time interval, will, for the sake ofbrevity, be called ignition lagby changing, that is increasing ordecreasing, the number of working cycles of the explosion chamber perunit of time, whereby the fuel can be injected at the instant at whichthe air velocity is the most favorable, advantageously upon the openingof the air valve. In this way the duration of the individual controlphases of a complete working cycle, as for example the scavenging, thecharging, and. the discharging of the high pressure combustion gasesfrom the chamber, can be increased or decreased. The absolute durationof the ignition lag can be kept constant at all cycle frequencies by sodetermining the control conditions that the instant of beginning of thefuel admission is not changed with reference to the instant of beginningof the air admission. In such case the fuel particles first entering thechamber always meet, at the moment they enter the chamber, a current ofair at the same favorable velocity at all cycle frequencies, so that thetime for conveying the mixture to the igniting place is always the same.

It will be understood that the best conditions of operation for anyparticular shape or size of explosion chamber can readily be determinedby preliminary tests in which the variable factors are adjusted untiloptimum results are obtained. Thus the necessary velocity of the fueland air stream could also be attained by correctly dimensioning thecross section of the passage way in the inlet members; aside from that,the pressures of the operating media could naturally also be suitablyselected with a view toward attaining a favorable ignition lag. Thatpath which the fuel must traverse in the chamber from the place ofadmission of the fuel to the ignition place should be made suiiicientlylong, as far as possible within practical limits, by suitably shapingthe chamber, so that the fuel will traverse this distance at a givenflow velocity only after the charging of the chamber has been entirelycompleted and the inlet members for the operating media are againcompletely closed or very nearly closed. By adequate dimensioning of thelength of this path it is further possible to admit the fuel with theair at about the-same time, and thus, under certain circumstances, witha small time displacement, between their respective admissions, so thatthe fuel particles first entering the chamber are carried along towardthe ignition place in a current of air of the highest velocity, which,according to experience, is most favorable for producing complete andhomogeneous mixture, the fuel being in fact torn along by such aircurrent.

-Finally, it is of course essential, in explosion plants in which theignition lag corresponds at least approximately to the correct operatingconditions, to employ one or anotherof the indicated methods foradjusting the ignition lag (afterregulation) 7 Several embodiments ofapparatus suitable for carrying out my improved ignition process areillustrated by way of example on the accompanying drawings. In saiddrawings,

Fig. 1 illustrates diagrammatically a section taken through a plantbuilt in accordance with the present invention, such plant operatingaccording to the constant volume explosion process;

Fig. 2 is a horizontal cross section through the control oil distributorof the turbine plant and is taken along the line II--H of Fig. 1;

Fig. 3 is a similar section through the control oil distributor alongthe line III-III of Fig. 1;

Figs. 4 and 5 illustrate certain of the valves of Fig. 1 in a differentposition of adjustment;

Fig. 6 is a time-pressure diagram representing the normal course of thepressure curve of a constant volume explosion chamber, the abscissaeindicating the time for the control processes in the explosion chamber,expressed both as the angular velocity of a hydraulic control device indegrees and in seconds, and the ordinates indicating the pressureprevailing in the chamber at any moment;

Fig. 7 shows a diagram drawn on a larger scale than that of Fig. 6 andillustrates only that section of the time-pressure curve which ispertinent to the present invention;

Fig. 8 shows a modification of the explosion turbine plant, the samebeing shown partly in elevation and. partly in section;

Figs. 9, l0 and 11 show details of the plant illustrated in Fig. 8 invarious positions of adjustment;

Fig. 12 is a diagram illustrating the timepressure relationships in theexplosion chamber which come into consideration upon displacement of thecommencement of the fuel injection with reference to the moment ofopening of the air charging valve;

Fig. 13 shows by way of example an arrangement for altering the controlperiods of the hydraulic control device which is adapted for chargingthe explosion chamber, in dependence upon the motor which drives suchcontrol device, the construction being shown for the most part insection; and

Fig. 14 is a section through the control device along the line XIV-XIVof Fig. 13.

The numeral I in Fig. 1 indicates an elongated cylindrical explosionchamber of the constant volume explosion type in which explosion gasesof high pressure are periodically generated, such gases being thendirected against the rotor 2 of the Curtis turbine T which is shown asprovided with two rings of blades. The explosion chamber is provided inthe usual manner with a scavenging air valve 3 at the conical inlet endof the chamber, the valve being arranged co-axially with the chamber,scavenging air of a pressure above atmospheric'being fed to the valvethrough conduit 4. The air valve 5 which charges air of a still higherpressure is likewise located at the conical inlet end of the chamber, asis also the fuel inlet member 6 in the form of an injection nozzle. Airis charged to the valve 5 under pressure through the conduit I, whilefuel is fed to the injection device 6 by conduit 8 leading from thepressure discharge side of a piston fuel pump B which is hydraulicallycontrolled in known manner. The pump B is connected with the explosionturbine T through a governor R which regulates the quantity of fuel fed.The gases generated by explosion in chamber I flow through the outlet ornozzle valve 9 arranged at the outlet end of the chamber which, like theinlet end, is of conical configuration, and are charged against therotor 2 of the explosion or impulse turbine T. In the cylindricalportion of the explosion chamber I there is provided an igniting devicell which serves primarily only for starting, such device being suitablyin the form of a spark plug. The explosion chamber is surrounded overits whole length with two cooling chambers II 'and I! which areindependent of each other. The cooling chamber I2 is the smaller andserves to cool the conical outlet end of the chamber I, at which end thenozzle valve 9 is located; while the cooling chamber ll surrounds theremainin and much larger part of the chamber, including the inlet end ofthe chamber. In the normal operation of the plant, a cooling agent isconducted to the cooling chamber H by thenpressure pump |3 throughconduit l4 and leaves'such chamber ,through the pipe l5 leading into aheat exchanger chamber H by the conduit H and is withdrawn from suchchamber by the conduit l8.

.tributor having a revolving disc or cylinder 25 which is rotated by amotor 21 through a drive 25. The conduits 29 to 23 are controlled by therevolving cylinder according to a definite working cycle in such amanner that each conduit is filled temporarily with a medium underpressure and is then again relieved of pressure. For this purpose, therotating disc is provided upon its circumference with a number of blocks28 (see Figs. 2 and 3), each two of which serve to control one of theattached conduits 20, 2|, 22 and 23.

Each two blocks lying in the same plane, to-- gether with thetwo-partsleeve 29 surrounding the revolving cylinder, form two separateannular chambers 39, 3|, the chamber 3| being constantly incommunication with the hollow interior 32 of the cylinder through atransverse port 3212 in the disc. This hollow interior,'which may beconnected with an air chamber 33, is filled with a compressed medium,such as pressure oil, introduced by'the conduit 34. The other chamber 30is connected with a space of lower pressure or with the atmosphere.Depending upon the position of the rotating cylinder, the conduit 20,2|, 22 or 23 is connected either with the pressure space 3|, so that theassociated member 3, 5, 9 or I9 is actuated, or with the space 30, atwhich time it is under reduced or under no pressure.

Fig. 2 shows the condition in which conduit 23 is covered by one of thecontrol blocks 28, so that upon further rotation of the cylinder 25 inthe direction indicated by the arrow, it is placed in communication withthe pressure space 3|, whereupon the pressure stroke of the fuel pump isinitiated. Fig. 3 shows a section through the control section of thedistributor 24 for the charging air valve 5, the associated conduit 2|being similarly covered by one of the control blocks. Thus if the blocks23 for the fuel pump and also those for the chargingair valve are soadjusted in reference to each other that the two associated oil conduitsare simultaneously placed under pressure and again relieved of pressure,the fuel will be injected into the explosion chamber simultaneously orat least nearly simultaneously with the beginning of the charging ofchamber with charging air.

The instants of introduction of charging air and .fuel may be displacedrelatively to each other. 'To this end, the upper part of the sleeve 29,all of which lies close to the rotating cylinder of the distributor, isarranged to rotate with reference to the lower, immovable section 290.This rotation is accomplished by means of a toothed segment 35 attached.to the upper sleeve section, and a drive 35 (see Fig. 2), which in turnis actuated by a segment 31. The latter segment is coupled by suitableconnecting means with the speed controlling governor R, as by beingconnected with the regulating sleeve 49 of the governor through lever85, link 31, bell-crank lever 88, link 89, bell crank lever 99, link 9|,92 and arm 93, as shown in Fig. l. regulates also the quantity of fuelfed in known manner, such regulation being effected .by adjustingvertically the fulcrum 35 of the lever 39,

which at its other end is articulated with the fuel pump piston l9, byshifting of the regulating sleeve 49 of the .governor. In this way,depending upon the position of the fulcrum 35, the spring pressedby-pass or return valve 4| is opened sooner or later by the roller 42acting through the linkage 42, or, when the maximum quantity of fuel isto be fed (when the operation is at full load). such valve is not openedat all. By the opening of the return valve the efiective feed stroke ofthe pump is interruptedto a greater or lesser degree, the fuel which isfed during the further course of the pressure stroke of the piston l9being forced back into the fuel suction conduit 44 by the pipe 43. Theconnection between the rotatable upper section of sleeve 29 with thespeed governor B may advantageously be accomplished in such manner thatsuch section in certain instances, for example upon adjustment of theinstant at which the injection of fuel begins, when the apparatus isunder test, can be displaced independently of the governor by hand. Thismay be done in simple fashion by making one of the elements of theconnecting mechanism 99-93 adjustable in length. Thus, as shown in Fig.1, the link 9|, 92 may be formed of two parts, the part 92 being in theform of a threaded rod which is received within a manually rotatable nut94 which is held against axial movement within the hollow end of thepart 9| but is free to rotate relatively to the latter. Rotation of thenut 94 will change the eifective length of the link 9|, 92, and thuscause adjustment of the upper section 29 of the sleeve 29, 29a. The nut94 may be held in adjusted position by the lock nut 95.

At 45 is shown a second heat exchanger which can be constructedsimilarly to the heat exchanger |6. The heat exchanger 45 serves innormal operation for re-cooling the compressed super-charging airdelivered by the compressor 46, the air flowing to the heat exchanger 45through the conduit 41, and after traversing such heat exchanger isconveyed to the charging air valve 5 through outlet 48 and conduit I.The medium for cooling .the super-charging air, preferably water, flowsto the heat exchanger 45 through the variable valve 49 and conduit 59,and flows oil at 5|. The super-charging com 'pressor 45 is driven by aturbine 52 or any other suitable driving motor, which at the same timedrives the scavenging air compressor 53, from which the compressed airflows in part through pipe 4 to the scavenging air valve 3, and in partto the super-charging compressor 45 through branch 54. Both compressorsmay be supplied inknown manner (see page 895, Figs. 47 and 48, of thehandbook Huette, 25th edition, Vol. III, Berlin, 1926, Wilhelm Ernst andSon) with'at least one intermediate cooling stage 45a or 53a, which,when necessary, can be cut out. The cooling agent enters the heatexchanger I at 55 and leaves the same at 55 through conduit 59 and Thegovernor' variable valve 51, such heat exchanger in normal operationserving as a re-cooler for the cooling agent of the explosion chamberoutlet section.

According to the present invention, various possibilities are providedfor feeding the two heat exchangers I6, 45, which will be described 'indetail hereinbelow in connection with the novel and improved mode ofoperation of the whole explosion turbine plant. The cooling agentfeeding conduit 50 is connected with the inlet 65 of the heat exchangerit through a branch conduit 59, and the cooling agent withdrawingconduit 56 is connected with the outlet SI of the heat exchanger 45through a branch conduit 60. The two branch conduits 59 and 60 have eacha valve Si or 62 by which they can be closed. Furthermore, there isprovided between the two branch conduits a connecting pipe 63 whichlikewise contains a valve 64. By reversing the two variable valves 51,49 into the position shown in Figs. 4 and 5, a hot medium instead of acooling agent may be fed into the heat exchangers. The purpose of suchreversal will be described hereinbelow.

The explosion plant so far described is operated in accordance with theinvention as follows:

To facilitate the understanding of the inventive idea, the mode ofoperation of the explosion plant will be explained with the aid of thetwo diagrams in Figs. 6 and 7, in which the ordinates indicate thepressure course in the explosion chamber during a complete workingcycle, while the abscissa: indicate the angular displacement of therotating cylinder 25 of the oil distributor 24 in degrees, a completerevolution of such cylinder corresponding to a complete working cycle,and being equal to 360 degrees. In Fig. 6, which represents a normaltime-pressure diagram of a known constant volume explosion chamber, thetime scale is indicated also in seconds for a complete working cycle forthe purposes of comparison. The working cycle is arbitrarily assumed tolie between two consecutive ordinate axes zz, during which, as stated,the rotating cylinder makes a complete revolution of 360 degrees. At theposition 0 the nozzle valve 9 is opened, the oil conduit 22 leadingthereto having immediately before been placed under pressure by thepressure oil distributor 24. The gases generated in the chamber I flowto the rotor 2 of the turbine upon opening of the valve 9. After thepressure of the gases have fallen approximately to the back or exhaustpressure, the scavenging air valve 3 begins to open at the point a, itsoil conduit 20 having been placed in communication with the oil pressureaccumulator space in the cylinder 25. Fresh air delivered by theconduit4 from the compressor 53 at a certain superatmospheric pressure is thenintroduced into the explosion chamber I through the open scavenging airvalve 3. The residual combustion gases in the chamber are driven outthrough the still open nozzle valve 9 by the incoming air which, due inpart to the peculiar shape of the chamber, takes the form of a piston,there being no whirls and eddies and thus no appreciable mixing ofresidual gases and air. When the chamber has been sumciently scavenged,the scavenging air valve closes, its oil conduit 20 being connected withthe low pressure space in the oil distributor 24. The nozzle valve 9 isclosed at the point b, its oil pressure conduit 22 having beendisconnected from the interior of the cylinder 25. After nozzle valvehas closed at point D, the air charging valve 5 and fuel inlet member 8begin to open, the oil conduits 2| and 23 being placed under pressure.Upon opening of the air charging valve, compressed air delivered by thecompressor 46, after passing through the heat exchanger 45 where heat isabstracted therefrom, is charged into the chamber I through conduit|,-while fuel is injected into the chamber by the pump B through theconduit 8 and fuel valve 6. The charging of the chamber with air andfuel occurs on the diagram of Fig. 6 along the interval 0 from the pointD to the point d. At the point d the mixture is ignited and theexplosion is ended at the point e, at which the next ordinate axis islocated. The expansion of the high pressure explosion gases through thenozzle valve 9 and the individual phases of the working cycle are thenrepeated in the above item described sequence. It'will be understoodthat the gases may exhaust from the turbine T under pressure, or at onlyatmospheric pressure,

and that the scavenging air pressure is at least '7 slightly higher thansuch exhaust pressure.

The ignition of the charge in the chamber occurs in the normal operationof the plant, according to the invention, at the highly heated surface Fshown in Fig. 1, which is adjusted between the combustible mixture inthe chamber to be ignited and the mass of gas or air located in theconical discharge end of the chamber. This ignition surface arisesduring the scavenging process, which takes place according to Fig.5between the points a and b, and is equal to the interval f. During thescavenging, in which the scavenging air displaces the residualcombustion gases from one end of the chamber to the other, there occursa strong heat transfer from the hot residual gases to the advancing,piston-like body of scavenging air. In order that no scavenging air mayescape through the nozzle valve 9, the latter is so controlled by theoil distributor 24 that it closes at the proper instant, preferably atthe point in which a certain amount of residual gases still remains inthe outlet end of the chamber, such amount of residual gases beingretained between the body of scavenging air and the closed nozzle valve.By this trapped quantity of gas the temperature of the adjoining layerof air, which has already taken up some heat during its travel from theinlet end of the chamber through the body of the chamber, isconsiderably increased. This temperature can, in accordance with theinvention, be further increased to a considerable degree by conducting acooling agent of very high temperature (hot oil, super-heated water,steam,

etc.) to the jacket l2 which surrounds the conical outlet of theexplosion chamber. This hot medium is circulated by the pump l3, suchcooling medium being only partially recooled in the heat exchanger IS inorder that it may return to the jacket l2 at a definitely hightemperature. I have found that the heating of the outlet section of theexplosion chamber is favored by giving the same a conical configuration,as due to the gradually decreasing cross section of such outlet endportion of the chamber, the gases discharged from the chamber during theexpansion period attain very high velocities. Aided by these highvelocities, a very vigorous heat interchange occurs in the wallet theconical outlet of the chamber, so that a large quantity of heat isstored in its walls. During the charging of the chamber I, a large partof this stored heat radiates into the rear portion of the chamber andhence into the already hot body of gas or air located at such end, as isindicated in Fig. 1 by the arrows. This heat radiation is transmitted tothe surface F directed toward the chamber mixture, which surface probably assumes a concave form. As a result of the radiation, the surface-F ultimately reaches a temperature which is suflicient to causeignition of the mixture in the chamber.

The same object of forming a large igniting surface F is attainedaccording to the invention under certain circumstances even when theresidual gases are completely driven out from the chamber. In such casesthe heat stored in the walls at the outlet end of the chamber isradiated into the body of air (scavenging air) collecting at such end inexactly the manner described above. A quantity of residual gases is, ofcourse, more effective as an igniting medium, as such gases already havehigh temperatures from the beginning, so that less time and radiant heatare required for developing the igniting surface F to kindlingtemperature than when pure air is located at the end of the chamber,the'original temperature of such air being far less than that of thecombustion gases.

In order to make clearer the action and superiority of the largeigniting surface F created in accordance with the invention, ascontrasted with the modes of ignition heretofore employed, namely, bymeans of an electric spark, there are shown circles of different sizesabout the spark gap of the igniting device 10 which projects into theinterior of the chamber. The function of this spark plug will bedescribed below. These circles indicate how the ignition of the chargeproceeds upon a gradually enlarging spherical surface from theoriginally very small electrical spark produced by the spark plug.Consideration of these circles of increasing size will show clearly thatat the moment of the initial ignition the charge in the chamber presentsa very small igniting surface. It is considered further that prior tothe ignition of the charge a certain amount of heat must be availablefor evaporating and on occasion for splitting up the fuel, which heatfor the greater partis withdrawn from the igniting mass of means, thenit will be evident that with such ignition the combustion can proceedonly slowly and incompletely. In any case, the igniting surface of aspark plug, which in its original condition presents a punctiformignition surface, can, due to the heat withdrawal above mentioned,develop only slowly into an effective, large igniting surface. Suchanigniting surface, moreover, at least during the first part of thecombustion, is exceedingly small in comparison with the surroundingunburned charge.

In accordance with the invention, there is presented to the mixture offuel and air in the explosion chamber, right from the instant at whichignition is initiated, a very large igniting surface F, which scarcelychanges in area from the beginning to the end of the combustion process.Moreover, the igniting area F, in comparison with the core of theignition mass (consisting of the gas or air located at the outlet end ofthe chamher) is only very small. In spite of the size of the ignitingsurface F, however, the quantity of heat radiating therefrom to themixture to be burned, which heat is necessary for evaporating, atomizingand decomposing the fuel, will be comparatively small, that is, small incomparison with the quantity of heat which is contained in the ignitingcore. The heat withdrawn from this igniting core for atomization of thefuel is always immediately replaced by the heat radiated from the highlyheated walls of the conical outlet of the chamber, so that the ignitingsurface F retains practically unchanged its original ignitingtemperature during the whole combustion process. In this way thereresults a very rapid and complete combustion of the fuel and air mixtureenclosed within the explosion chamber.

In Fig. 7, which presents on a larger scale than Fig. 6 only thosephases of the working cycle of the explosion chamber which need beconsidered in connection with the present invention, the effect of myimproved mode of ignition is graphically illustrated. The full-linecurve indicates again the time-pressure curve of the normay explosiondiagram according to Fig. 6, in which the ignition of the combustiblemixture in the explosion chamber is effected in known manner with theaid of a point ignition. The reference characters a, b, c, d, e and ffor the dif ferent phases of the process have the same meaning as inFig. 6. The point d thus again indicates the moment of ignition. Fromthe course of the rising explosion line g beginning at this point andending at the point e it will be seen upon simultaneous consideration ofthe abscissa time scale, that the combustion occurs comparativelyslowly; the combustion is particularly slow from the point h on, atwhich instant the pressure in the chamber is about 25 atmospheresabsolute. The course of the combustion line 9; from the point h to thepoint e leads to the conclusion that the combustion of the mixture isnot yet entirely completed at the point e, so-that during the expansionphase from the point e to the point a a strong after-combustion takesplace.

When, however, the explosion chamber operates according to the methodproposed by the present invention, according to which the charge in thechamber is ignited at the large igniting surface F of the air or gasmass located at the outlet end of the chamber, the pressure-line ischanged as is indicated on the diagram by the dotted 'line i. The chargeis ignited at the instant k, the spark plug [0 being connected to adistributor by a cable 96 (Fig. l) in known manner, the distributorbeing geared to the motor 21 and thus properly synchronized with thevalve controlling mechanism. From the steepness of the line i it will berecognized that the combustion takes place considerably more rapidlythan is the case with known ignition at a point, represented by theexplosion line g shown in full lines. The charge is completely burned inmy improved igniting process at the instant m. This will be clear in thediagram from the fact that the line i falls beyond the point 111. downto the point 11., at which instant the expansion of the explosion gasesbegins as the nozzle valve commences to open; there occurs during theinterval mn a definite pressure drop in the chamber due to the transferof heat to the walls of the i explosion chamber. If, now, the opening ofthe nozzle valve is advanced to the point m at which instant the chargeis fully burned, the expansion of' the explosion gases beginning at suchpoint would proceed according to dot and dash curve I. The pressure ofthe combustion gases at the moment of opening of the nozzle valveamounts to about 28.25 atmos., absolute while in an ignition processinvolving ignition at a point, the pressure at the instant e amounts toonly about 28.15 atmos. absolute. These values for the pressure at thebeginning of the expansion phase have been established by carefulinvestigation, the air, pressure and other conditions being of coursethe same, and confirm and support the statements given hereinabove.

From both of these pressure values it follows that the increase inpressure of the combustion gases resulting from the practice of thepresent invention amounts to about 12% of the pressure obtained withignition at a point, assuming that the amount of fuel and the ratio offuel to air are the same in both. cases. Corresponding to this increasedpressure rise, there is obtained of course a larger energy output fromthe combustion gases in my improved process. In the investigationsconducted by me the improvement in the combustion attained in accordancewith the invention was apparent also from the fact that, while theexhaust during the operation with punctiform ignition was always cloudy,which as known is attributable to poor combustion, with combustionaccording to my novel process the exhaust was completely colorless andodorless.

The above-described novel ignition process makes it necessary to providespecial auxiliary measures for the starting of the explosion chamber Ifrom the cold condition, as at such time the air entering the explosionchamber can not take up any heat in view of the absence of residualcombustion gases and in view also of the low temperature of the walls ofthe chamber, which remain comparatively cool for quite a number ofcycles and can therefore receive no suflicient heat.

If easily, ignitable fuel is used in the operation of the explosionchamber, an igniting device In in the form of one or more electric sparkplugs may be employed for starting. As soon as normal operatingconditions prevail in the explosion chamber, these auxiliary ignitingdevices can again be cut out, so that in the further course of operationof the chamber, that is, after the air or residual gases occupying theoutlet end of the chamber during the charging are heated to thenecessary igniting temperature by radiation, the ignition of the chargesoccurs at the ignition surface F. For the sake of insuring ignition, oneor more of the above-mentioned igniting devices Hi can be permitted tocontinue operating during the normal operation of the explosion chamber.Such safety igniters are above all advantageous when the gases generatedin the explosion chamber are used for operating a machine whose load andspeed vary frequently and widely so that, due to these fluctuations, thecharging conditions of the explo sion chamber are changed suddenly andvery abruptly. If such auxiliary igniters are permitted to operateduring the normal functioning of the chamber, they are preferablycontrolled in such manner that they become active after the normalignition instant of the surface F, the distributor being made adjustableas is well known in the art. In this way the auxiliary ig niters cannotdisturb the normal ignition operation by the ignition surface F, but incase of failure of proper functioning of such surface they initiate theignition.

The starting of the explosion chamber from the cool condition can befavored in accordance with the invention in the case of diflicultlyignitable fuel by conducting the charging air into the chamber in ahighly heated condition. To this end, the air is passed through apre-heater before it is admitted into the explosion chamber. If are-cooler. is provided for the normal operation of the plant forre-cooling the compressed charging air in order to obtain a large weightof air per charge, then such re-cooler may with advantage be operated asan air preheater during the starting period by conducting a hot medium,-such as steam, therethrough. The conditions on starting of the explosionplant are especially favorable when the outlet end of the explosionchamber is artificially pre-heated, so that the temperature of the airconfined at such end is raised.

The pre-heating of the charging or scavening air and of the outlet endof the chamber may be accomplished with the apparatus shown by way ofexample in Fig. l by operating the two heat exchangers l6 and 45, whichin the normal operation of the plant function as re-coolers, aspreheaters during the starting period. In order to obtain such resultthe two reversing valves 49 and 51 are brought into the position shownin Figs. 4 and 5. Assuming that the two heat exchangers are to operatein series as pre-heater, the valves El and 62 are closed while the valve64 in pipe 63 is opened. In the position of the reversing valve 51according to Fig. 4, a heating medium, for example steam, flows throughthe conduit 66 and through the conduit 56 first to the heat exchanger itwhere the steam after giving up a part of its heat to the mediumcirculated by the pump l3, flows on at the exit v65 to the heatexchanger 45 through the open conduit 63. In the latter the steam givesup its residual heat to the air flowing through the exchanger from thecompressor 45 and flows finally through the conduit 50 and reversingvalve 49 into the discharge conduit 61.

The temperature of the pre-heated air can, when necessary, be raised byarranging the two heat exchangers in parallel. In such case the valve 64is closed while the valves 6| and G2 are opened. The heating medium fedby pipe 66 passes through the reversing valve 51 and then flows in partthrough the conduit 56 into heat exchanger 16 and in part through theconduit 60 into the heat exchanger 45. Both heat exchangers are thustraversed by a heating medium of the same temperature. The streams ofheating agent leaving both heat exchangers meet at the junction ofconduits 50 and 59 in advance of the reversing valve 49 and afterpassing through such valve flow off through the conduit 61.

Finally, by closing the valves 62 and 64, the beat exchanger l6 can beused alone as the preheater. In such case only the air or gases confinedwithin the outlet end of the explosion chamber are heated, if the heatexchanger 45 is not heated in some other fashion; similarly, only thecharging air could be heated during the starting of the plant. Thepre-heating of the air can be increased to a considerable extent bycutting out of operation the intermediate cooling stages 46a. and 53a,respectively, of the two compressors 4B and 53, or only one of suchstages could be cut out, as by arranging suitable valves 98, 99 in theconduit 91 which supplies the cooling agent, the latter being withdrawnthrough conduits llllland HH.

As soon as the explosion chamber has reached the condition of normaloperation, the two valves 49 and 51 are reversed into the positionsshown in Fig. 1. There then flows a cooling agent instead of a heatingagent into the exchangers, such cooling agent flowing through theconduit 58 and reversing valves 49, while the heated cooling agent,following the heat interchange, flows of! through valve 51 and conduit58a. to be recooled or discharged. The heat exchangers which now operateas re-coolers can be operated in the same way as was described inconnection with their operation as pre-heaters by suitable adjustment ofthe valves 6|, 62 and 64. In other words, the heat exchangers can bearranged either in series or in parallel, or the cooling agent deliveredby the conduit 58 can be circulated through only one or through bothheat exchangers. If the heat exchangers are arranged in series, then thecooling agent, contrary to the operation of the apparatus as preheaters,flows first through heat exchanger 45 for the charging air andsubsequently through the heat exchanger l6 for recooling the coolingagent of the outlet end of the explosion chamber. With such mode ofoperation the requirement that the cooling agent for the chamber outletend be only partially recooled is met in the most satisfactory manner,so that there remains stored in such cooling agent the necessary radiantheat for the formation of the hot igniting surface F.

The pre-heating of the outlet end of the chamber and of the airintroduced into the explosion chamber for starting the plant, can beaccomplished in still other ways. Fig. 8 shows one way of bringing aboutsuch result in a manner difierent from that shown in Fig. 1. In Fig. 8the numeral i again indicates the explosion chamber, T the turbine, 3the scavenging air valve, 5 the charging air valve,.6 the fuel injectorvalve, 9 the nozzle valve, It the heat exchanger for the chamber outletend, with the interposed circulating pump l3, and 45 the heat exchangerfor the charging air. The construction of Fig. 8 diifers from that ofFig. 1 only in that for starting, two

separate pre-heaters 68, 69 are provided which are arranged in series,for example, by means of the connecting conduit 10. The heat exchangersit, thus operate. only as re-coolers which are cut out of operationduring starting. The preheater 68 is heated by a burner Ii to which airis fed by conduit I2 and fuel by conduit E3. The

hot combustion gases give up a part of their heat in the exchanger 68and then flow through conduit iii to the space I! of the secondpre-heater st for the charging air, whence they flow in the directionindicated by the arrow through the heating tubes Ha which by way ofexample are shown as of U-form. The gases leaving the heating tubesreach interconnected collecting spaces 75, which they leave through thedischarge pipe it.

The air delivered by the compressor flows in the normal operation of theplant through the threeway valve Ti, conduit 18 into the recooler 45 andsubsequently flows through the conduit '5 con nected therewith to thecharging air valve 5. A check member 18a is positioned in the conduit 1and is open during normal operation. Upon starting of the plant thevalve I1 is brought into the position shown in Fig. 11, so that thepassage to the conduit 18 leading to there-cooler 5 is cut ofi. The airthen flows through the air heater 69 and, through the conduit 19 intothe conduit I to the charging air valve 5. The conduit 19 likewise isprovided with a check device We which after v valve 8|. Upon starting,the recooler i6 is cut out by reversing the valves 80 and 8|, as shownin Figs. 9 and 10. In this position of the valves,

the medium circulated by the pump I3 is forced through the conduit '2leading from the valve 88, through the heating coil 83 of the pre-heaterB8 and finally through conduit 84 and three-way valve 8| back to thepump l3, whence it is conveyed in strongly heated condition to thechamber outlet end, so that the latter becomes heated. As soon as theexplosion chamber has reached its condition of normal operation, thepro-heater 68 is cut out by moving the valves some 8! back to thepositions shown in Fig. 8, so that the pump l3 circulates the coolingmedium of the cooling space I! through the re-cooler l6.

The present invention provides also a method of determining the instantor ignition o! the fuel and air mixture with reference to the availablecharging time in such a way that the ignition always begins after theformation of a homogeneous, combustible mixture of fuel and air withavoidance of pre-ignition. In the embodiment of the inventionillustrated in Fig. l, the adjustment of the instant of ignition isaccomplished by a time-displacement of the instant of fuel introductionwith reference to the instant at which the charging of air is begun. Forthis purpose. the upper part of the intermediate sleeve 29 o! thedistributor M which has the function of controlling the oil conduit 23of the fuel pump B is rotated a suitable distance by the toothed segment3'! relatively to the lower, fixed part 29a of the sleeve as, 290. Thisadjustment is made by hand upon starting the explosion plant, while whenthe plant is in operation such adjustment can be efiected alsoautomatically in dependence upon the governor R when the adjustingmechanism 35, 36, 3?, of the upper sleeve part is connectedwith thegovernor B. through a suitable conhection as shown in Fig. l. The timeinterval necessary for the travel of the fuel from the point ofintroduction into the chamber toward the ignition place becomes largerthe later the fuel pump B begins its eifective feeding stroke.

The way in which the control of the instant of ignition afl'ects thetime-pressure diagram is shown in Fig. 12. This diagram shows betweenthe ordinate axes Z the course of the pressure curve in the explosionchamber during a complete working cycle with the individual processphases s'milar to the pressure course illustated by the diagram in Fig.7, where the ignition oi the fuelair mixture occurs at the instant k andthe opening of the nozzle valve at the instant n. The dotand-dash line 0in Fig. 12 indicates the pressure diagram or the super-charging air, andthe long dash line p the pressure curve ofthe scavenging air in advanceof the corresponding valves, and the short dash line a the counterpressure behind the nozzle valve. All of these curves are drawn to thescale shown at the left of the ordinate axis in atmospheres absolute.The point line 1' represents the fuel pressure in the delivery conduit01' the fuel pump during the whole pressure stroke, the scale for suchcurve being indicated in atmospheres absolute at the right of theordinate axis. The movements of the inlet and outlet valves of theexplosion chamber are shown at the bottom of the diagram, the full lineA representing the valve lift diagram 01' the nozzle valve, the dashline B that of the scavenging air valve, and the dot and dash line Cthat of the super-charging air valve. The abcissa scale is given inangular degrees based on a complete revolution of the oil-' distributorwhich oontrolsall the ,valves, beginning at zero degrees at the momentof opening of the nozzle valve, and is given also in seconds,

it being assumed by way of example that a complete cycle, that is'asingle complete revolution of the rotating cylinder of the oildistributor requires 0.72 sec. Upon opening of the nozzle valve at thepoint 12, the high pressure gases expand out of the explosion chamberdown to the point a, at which instant the scavenging air valve isopened. The latter is again closed at the instant t. Shortly thereafterthe nozzle valve also closes, the same being completely closed at theinstant u. At about the same time, the charging air valve, whichsupercharges the chamber with air of higher pressure, opens at theinstant b, so that the high pressure charging air flows at high velocityinto the explosion chamber filled with scavenging air of .lowerpressure. At approximately the beginning of the introduction of thecharging air the fuel pump begins its pressure stroke at the instant v,in the present case about 120 in advance of the opening of the nozzlevalve. The actual injection of the fuel begins at Y the point w when thepressure in the fuel conduit leading to the injection nozzle overcomesthe pressure tending to keep such nozzle closed. The fuel injectiontherefore occurs a certain interval of time after the beginning of thecharging air admission, that is, at an instant at which the originalhigh air velocity has fallen to a definite value, as the counterpressure in the explosion chamber rises as the charging proceeds. Thefuel thus meets an air stream of lower velocity the later the injectionof the fuel begins with reference to the beginning of the air charging.The smaller the air velocity, the longer will be the time consumedbefore the first fuel particles are carried forward to the ignitionpoint It and the ignition is effected. According to the invention, theinstant to at which the fuel injection begins, is to be so adjustedinthe embodiment shown in Fig. 1 this is accomplished by rotation of theupper sleeve part 29 of the oil distributor 24-- that the instant y ofclosing of the charging air valve and the instant e at which the fuelinjection is ended come to occur in advance of the ignition point k,that is, within the interval a: (ignition lag). In other words, theignition of the fuel-air mixture always occurs only after the chargingair valve and the fuel valve are again closed, so that the combustiongases cannot penetrate into the conduits leading to such valves.

If, however, it should be desired, with a view to obtaining goodatomization of the fuel, to utilize for such atomization the maximumflow velocity of the air which prevails at the beginning of the chargingair admission, so that the beginning of the charging air and fueladmission coincide at least approximately, such result can berealizedaccording to. a further development of the invention by changingthe cycle number of the explosion chamber. As the cycle frequency isfixed by the velocity of the oil distributor, which is equivalent to anyother mode or mechanism for control, the rotational speed of thecylinder of the distributor is accordingly altered. In this way the timescale is varied with reference to the degree scale, and hence the lengthof the ignition lag x, which depends only upon the time scale is changedwith reference to the other nagnitudes (control phases of a workingcycle) which vary in point of time with the cycle number, that is withthe rotational speed of the oildistributor (control shaft speed); theseother magnitudes (control phases) depend only upon the degree scale.

Fig. 13 shows by way of example an arrangement for varying the cyclefrequency in the manner above described. 'The numeral 84 indicates anoil distributor which differs from the distributor 24 shown in Fig. 1only by the omission of a two part intermediate sleeve 29 arrangedbetween the distributor housing and the rotating cylinder 25 and theactuating mechanism for such sleeve. The rotating cylinder is driven asusual from the electric motor 21 through the drive 26. Current issupplied to the motor from the line 85 through a regulating resistance86. With the aid of this resistance it is possible to vary therotational speed of t he motor and of the distributor cylinder, and thusalso the cycle frequency of the explosion chamber, which results in achange of the ignition process in the manner explained above.

It is of course obvious that my improved method of operation and thevarious details of apparatus are not limited to the specific form of theinvention above described and shown on the drawings. Also, theindividual features of my improved process need not all be usedtogether, as certain fea-' tures can be used without others.

I claim:

l. The method of operating elongated constant volume explosion chamberssuitable for use in explosion turbines and having air and fuel inletmembers arrangedat one end thereof, and an outlet member at the oppositeend thereof, said method comprising confining a gaseous medium betweenthe outlet member of the chamber and a new charge of air and fuelentering and occupying the chamber, closing the chamber when the chargeof air and fuel has been admitted into the chamber, and causing saidmedium to assume sucha temperature that at the surface of contactbetween such medium and the said charge the ignition temperature of thecombustible mixture formed in'the chamber prevails and directlyinitiates the combustion of such mixture.

2. The method according to claim 1, including the steps of displacingthe residual gases of a previous explosion with the combustion air ofthe next cycle, and closing the outlet member of the explosion chamberbeforeit is reached by the new charge of air being introduced into thechamber.

3. The method according to claim 1, including the steps of displacingthe residual gases of a previous explosion with the combustion air ofthe next cycle, and closing the outlet member at an instant at which acertain amount of residual combustion gases is trapped in the chamber atthe outlet end section thereof.

4. The method according to claim 1, including the step of cooling theoutlet end section of the explosion chamber to so limited an extent thatthe temperature of the gaseous medium is effectively increased byradiation of heatfrom the walls of the explosion chamber.

5. The method according to claim 1, including the steps of cooling theoutlet end section of the explosion chamber to so limited an extent thatthe temperature of the gaseous medium is effectively increased byradiation of heat from the walls of the explosion chamber, and likewisecooling the main body of the explosion chamber with a cooling agent, thetemperature of the cooling agent for the outlet end section beingmaintained higher than that of the cooling agent of the main body of thechamber.

6. The method according to claim 1, including the step of subjecting thecombustible charge in the chamber tom additional ignition which becomeseffective at an instant after that predetermined for the ignition by thegaseous medium.

7. The method according to claim 1, including the step of conductingexternal heat to the isniting gaseous medium at the starting of the ingthe step of conducting external heat to the igniting gaseous medium atthe starting of the chamber to develop in such medium the temperaturecondition at which it effects ignition, and heating the air prior to itsadmission into the explosion chamber during thestarting of the chamber;

10. The method according to claim 1, including the step of preheatingthe agent which in normal operation serves to cool theoutlet end sectionof the chamber, and likewise the air, at the starting of the chamber todevelop in said gaseous medium the temperature condition at which iteffects ignition.

llQThe method according to claim 1, including the step of conveying thefuel by air toward the outlet end of the chamber, and dimensioning theinterval during which the fuel is conveyed to the ignition placeincorrespondence with the control time determined by the cycle frequencyof the process 'by suitably adjusting the fuel carrying air velocityprevailing at the beginning of the formation of the combustible mixture.

12. The method according to claim 1, including the steps ofconveying-the fuel by air toward the outlet end of the chamber, anddimensioning the interval during which the fuel is conveyed to theignition place in correspondence with the control time determined by thecycle frequency of the process by suitably adjusting the fuelcarryingair velocity prevailing at the beginning of the formation of thecombustible mixture, and so adjusting the velocity of the fuel-carryingairthat the ignition occurs when the inlet members close or are closed.-

13. The method according to claim 1, including the step of conveying thefuel by air toward the outlet end of the chamber, dimensioning theinterval during which the fuel is conveyed to the ignition place incorrespondence with the control time determined by the cycle frequencyof the process by. suitably adjusting the fuel-carrying air velocityprevailing at the beginning of the formation of the combustible mixture,and opening the fuel inlet member later with reference to the instant ofopening of the air inlet member according as the moment of ignition isretarded.

14. The method according to claim 1, including the steps of conveyingthe fuel by air toward the outletv end of the chamber, dimensioning theinterval during which the fuel is conveyed to the ignition piaceincorrespondence with the control time determined by the cycle frequencyof the process by suitably adjusting the fuel-carrying air velocityprevailing at the beginning of the formation of the combustible mixture,and retarding the instant of ignition by opening the fuel inlet memberonly when the back pressure in the combustion-chamber has reached apredetermined value, as the charging of the air proceeds.

15. 'Ihe method according to claim 1, including the steps of conveyingthe fuel by air toward the outlet end of the chamber, dimensioning theinterval during which the fuel is conveyed to the ignition place incorrespondence with the control time determined by thecycie frequency ofthe,

process by suitably adjusting the fuel-carrying air velocity p evailingat the beginning of the formation of the combustible mixture, andoperating the chamber at a cycle frequency at which the instant ofignition occurs after the air and fuel inlet members are closed.

16. In an explosion plant, the combination of a constant volumeexplosion chamber having air and fuel inlet mechanism at one end thereofand outlet mechanism for the explosion gases at the opposite endthereof, timing mechanism for so operating the air inlet and the outletmechanism that the air inlet mechanism is opened while the outletmechanism is still open following the expansion of the explosion gases,means for charging fuel under pressure to the fuel inlet mechanism afterthe charging of air into the chamber has begun, and means whereby thebody of gas at the. outlet end of the chamber is caused to have such anelevated temperature by the time that the advance portion of fuelreaches such body of gas, that ignition of the fuel and alrmixture iseffected along the surface of contact between such body of gas and thefuel and air mixture.

1'7. The combination set forth in claim 16, wherein the last mentionedmeans comprises acooling jacket about only the outlet end of thechamber, and a pump for circulating through said jacket a cooling agenthaving so nearly the temperature of the wall at said outlet end thatsaid end is subjected to a limited degree of 0001-:

18. The combinationset forth in claim 16, wherein said timing mechanismis constructed to cause closing of the outlet mechanism at such anadvanced instant that enough residual gases are trapped at the outletend section of the chamber to fill such section.

19. The combination set forth in claim 16, wherein the outlet endsection of the chamber is of conical coation, and wherein said timingmechanism is constructed to cause closing of the outlet mechanism atsuch an advanced instant that enough residual gases are trapped at theoutlet end section of the chamber to fill such section.

20. The combination as set forth in claim 16, wherein the air inletmechanism includes-means for charging air of high pressure for conveyingthe fuel toward the outlet end of the'chamber, and wherein the-chamberis ofsuch length that the fuel and air mixture reaches the place, ofignition only after the fuel inlet member has closed.

21. In a constant volume explosion plant, the combination of anelongated constant volume explosion chamber having air and fuel inletmembers arranged at one end thereof and an outlet member at the oppositeend thereof, said inlet mechanism adapted to introduce periodically acharge of air which displaces the residual gases remaining in thechamber from the previous explosion, timing mechanism for said inlet andoutlet members constructed to close the outlet member before the advanceportion of incoming air reaches the same, thereby to trap a body of gasat the outlet end section of the chamber, a jacket about the outlet endsection of the chamber, a separate jacket about the main body of theexplosion chamber, and means for circulating separate bodies of coolingagent through said jackets,

the temperature of the cooling agent traversing the first jacket beinghigher than that of the cooling agent traversing the second jacket,

whereby the chamber wall at the outlet end section is maintained at ahigher temperature than the main body of the chamber and the temperatureof the trapped body of gas is effectively inoreawd by radiation of heatfrom said end section to the ignition temperature of thecombustible'mixture formed in the chamber.

HANS HOLZWARTH.

